Sash-balance



(No Model.)

B. A. GRANT.

, SASH BALANCE.

No. 575,926. Patented Jan! 26, 1897.

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UNITE STATES PATENT OFFICE.

ROBERT A. GRANT, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR OF ONE- HALF TOELIJAI'I A. SHAW, OF LEXINGTON, MASSACHUSETTS.

'SASH-BALANCE.'

SPECIFICATION forming part of Letters Patent N0. 575,926, dated January26, 1897'.

' Application filed November 30, 1896. Serial No. 613,935. (No model.)

To (all whom it nmw concern.-

Beit known that LROBERTA. GRANT, asubject of the Queen of Great Britain,residing at Cambridge, in the county of Middlesex and State ofMassachusetts, have invented a new and useful Counterpoise forWindow-Sashes and the Like, of which the following is a specification,reference being had to the accompanying drawings, in which- Figure 1 isan elevation of my counterpoise. Fig. 2 is an elevation of a modifiedform. Fig. 3 is a plan of Fig. 1, and Fig. 4 is an elevation showing awindow with its lower sash attached to my counterpoise.

My invention is a counterpoise for windowsashes and the like, and isdesigned to take the place of the weights and pulleys now in common use.

My invention is the combination of a window-sash or the like whoseweight is to be counterpoised provided with cords with a drum or roll towhich the cords are attached, which drum or roll is connected to aspring which exerts its force to cause the drum to turn, thus windingthe cords upon it and aiding in lifting the weight attached to thecords.

In the drawings, A is the sash, to which are attached the cords B B,which are also attached to the periphery of the drum 0. The shaft ofdrum 0 carries the pinion a, which meshes with the toothed wheelD, whoseshaft carries the cam H. The spring E, one end of which is secured tothe window-casing, is secured to the cam H by means of flexibleconnections e in such a manner that when the sash is down, as shown inthe drawings, the connection e is wound on the cam H, and when the sashis raised the force of the spring causes the cam I-Ito turn, thusturning the wheel D and through it the drum 0 and winding the cords onthedrum. It is clear that when the sash A is at the position shown inthe drawings the spring E is stretched to its greatest length and isconsequently exerting its greatest force, which force diminishes in 5 adirect ratio as the length of the spring diminishes.

In order to equalize the force of spring E,

I attach one end of it by flexible connections 6 to the cam H, so thatwhen the sash is down and the spring exerting its maximum power there isa small leverage to aid the spring in turning the wheel D, but as thewheel turns and the power of the spring diminishes the leverage in favorof the spring increases, so that by a proper construction of the cam Hand spring E a uniform force will be exerted by the spring throughoutthe entire operation of raising the sash.

In Fig. 2 I have shown a modified form of my counterpoise, in which thespring is attached by flexible connection 2 to a wheel D, which carriesa toothed cam H, mounted on it. Toothed cam H intermeshes with toothedcam H on wheel D. By using the wheelD and its cam 1-1, I am able tostretch the spring much farther than by using only the wheel D and camH, for in the form shown in Fig. 1 the connection e is only wound aroundthe face of cam H, while in the form shown in Fig. 2 the connection 6 iswound periphery of wheel D.

It is obvious that my invention may be applied to sliding doors,dumb-waiters, and the like without any material change in construction.

What I claim as my invention is The combination of sash A and its cordsB B with drum 0, wheel D 5 cam H mounted on wheel D and spring E one endof which is 80 fast tothe window-casing and the other to cam H; allcombined to allow springE to exert its power to turn drum 0 and therebyraise the sash, substantially as described.

ROBERT A. GRANT.

around the Witnesses:

JOHN R. SNOW, WILLIAM MAYNADIER.

